As the earth has grown in population, the skyscrapers have been built to effectively use the limited area of land. Therefore, when the fire breaks out in the skyscrapers, the interior furniture formed of flammable and toxic material and equipped in the skyscrapers may cause a disaster.
Furthermore, when the fire breaks out, the fire escape and hallway may function as a chimney that quickly sucks up the toxic gas and flame and the whole building becomes a sheet of flames.
In addition, when the fire breaks out, since the main/front door of the building cannot be used, people who are in the building have to escape out of the building through a window or a veranda. Therefore, people who cannot be rescued in advance may be victims by the flame and toxic gas or by leaping down from the building. In emergency situations such as the September 11 terrorist attack in the U.S., many peoples were victims while working down the narrow flights of the stairs.
Accordingly, descending life lines have been used in case the fire or other emergencys break out. That is, the people can escape out of the building through the window or veranda using the descending lifelines.
However, the conventional descending lifelines have a problem in that it cannot be used above a tenth floor. Furthermore, the descending life is designed to be used for one by one.
Furthermore, the conventional descending lifelines are complicated in use, having a limited function. Therefore, the frequency in use of the conventional descending life is very low even in an emergency.
In addition, since the conventional descending lifelines are designed to operate by an electric power, it may not work when the fire breaks. That is, when the fire breaks out in the building, the electric power line may be damaged not to supply the electric power to the descending lifelines.